Indication light



March 4, 1958 Filed July 14, 1954 J. H. SCHELLMAN ETIAL INDICATION LIGHT 2 Sheets-Shet 1 March 1958 J. H. SCHELLMAN ET AL 2,825,896

INDICATION LIGHT 2 Sheets-Sheet 2 Filed July 14, 1954 m M y WM flma M a Wm W United States Paten Q INDICATION LIGHT loseph Henry Schellman, Ridley Park, and William Robert Law, Havertown, Pa., assignors to Hetherington, Inc., Sharon Hill, Pa., a corporation of Delaware Application July 14, 1954, Serial No. 443,404

Claims. (Cl. 340-252) The present invention relates to indicator lights of he character employed in connection with electric cir- :uits especially on aircraft.

A purpose of the invention is to increase the light ransmitted from an indicator light by providing a reiector at the end of the barrel which engages the transrarent cover.

A further purpose is to displace the lamp so that its ight-giving portion is all between the reflector and the nd of the transparent cover remote from the barrel.

A further purpose is to simplify and improve the contruction of the test switch in an indicator light so that itficulty will not be encountered by twisting of the parts nd so that contact will be made more reliable in both 1e normal position and the test position.

Figure 1 is a side elevation of an indicator light and Witch combination in accordance with the invention.

Figure 2 is a rear elevation.

Figure 3 is an exploded side elevation partly in axial action showing the lamp and indicator cover and bar- :1 to enlarged scale.

Figure 4 is an enlarged axial section taken on the line 4 of Figure 2 showing the test switch in open posion.

Figure 5 is an exploded perspective of the indicator ght and test switch combination of the invention.

Figure 6 is an axial section showing a variation in him the indicator light assembly is employed without to test switch.

Indicator lights are extensively used where electrical antrols are employed, particularly on aircraft, to show 'hat circuits are closed. These devices frequently are rovided with test switches so that on pushing the light can be connected to a test circuit to test the bulb and ermissibly to indicate the operativeness of other ciriit connections.

Difiiculty has been encountered in the prior art in number of respects. Many of the .test lights have not .ven sufiicient illumination so that it was necessary to se excessively high candle powers.

In the present invention a small but very efficient reactor has been placed on the end of the barrel to proct a maximum of light into the area of vision. Furtermore the cover and barrel assembly has been redegned so that the light-giving portion of the bulb is 10- lted toward the observer with respect to the reflector.

In certain of the prior art constructions it has been ificult to replace the bulb and has been necessary to lgage the contact by pliers. In the present device, the inge on the bulb is carried out beyond the diameter the barrel so that the bulb can readily be pulled out it! grasped by the fingers.

In prior art devices the switch construction has been IlTlPiiCfitfid and expensive and has given trouble through ireliability of contacts. In the present invention the :vice has been simplified and made mone reliable, and

2,825,896 Patented Mar. 4, 1958 the indicator light in place by engagement with the:

thread 24.

The housing is tubular and hollow and has near its: forward end engaging the inside of an inwardly directed flange 23' a tubular insulating cup 27 which at suit-- ably diametrally opposite positions is longitudinally interiorly ribbed toward the rear at 27, as later discussed. The cup 27 at the rear has a disc-like bottom 28 having a central longitudinal opening 29, and a longitudinal opening 30 at one side through which passes the tab 31 of a fixed metallic contact 32 extending over the side of the bottom 28 toward the forward end. The contact 32 has a central opening 33 in line with the opening 29 in the bottom and a notch 34 which engages around one of the ribs 27' and prevents the contact 32 from turning.

Rearward of the insulating cup 27 and fitting the inside of the housing is a tubular insulating sleeve 35 which extends to near the rearward end of the housing, at which point the housing receives an insulating disc 36 engaging the insides thereof and held by crimping of the rear of the housing at 37.

On the side of the disc-like bottom 28 toward the disc 36 is placed a central normal lighting switch contact 38 which has an interior opening 40 in line with openings 29 and 33, and the contact 38 has a rearwardly extending tab 41 which narrows at 41 to form a shoulder 42 and passes through an opening 43 in insulating washer 36, thus holding the contact in position by the engagement of the shoulder 42 against the insulating washer. The washer 36 also has an opening 44 which passes the tab 31 of the contact 32.

Inside the washer 36 at the center is located a transverse portion of a switch fixed contact 45 which has a central opening 46 and is held by rivet 47 passing through a central hole in the disc 36. A tab 48 from this contact passes through an opening 49 in the disc 36 and is visible at the rear of the indicator light.

Inside the insulating cup 27 and slidable with respect to it is a forwardly extending tubular casing 50 which is internally threaded at one end and receives externally threaded portion 52 of barrel 51. The barrel is preferably reduced in diameter at both sides of the threaded portion 52. At the forward end of the barrel it is preferably enlarged and forms a reverse conical reflector surface 53 which may be used as machined, but it is desirably ground or otherwise smoothed for maximum effectiveness, and is preferably of a metal which forms a good mirror surface such as nickel plated brass. The barrel at its forward end is joined suitably by molding to a transparent cover 54 around the enlarged portion 53' of the barrel and in direct contact with the reflector surface 5'3. The plastic cover may be embedded in recesses on the outside of the barrel, not shown. The cover is suitably of a transparent plastic such as cellulose acetatebutyrate, methyl methylacrylate, or polystyrene. The interior of the dome of the cover 54 desirably conforms closely with the curve of the dome of the illuminating portion of electric light bulb 55 so that the bulb fits snugly in the hollow of the cover and its illuminating portion is desirably all forward of the rearward edge of the reflector. 53.. vThesocket portion .5 6 of sthenbulb. e t nds. through the barrel and at the rearward end the bulb has an enlarged flange 57 whichslsticks out slightly at 58 bey ndit-heitoutsideiofvthenhavnel isosthatzthebulbrle nz. grasped by the fingers. The bulb makes Q contac... theisbarrel a around:;:.its z-meta-llicn socket wpostion :15 has :a SGnd3C,OI1IflCl2;59,%-'at .the center-bf gthe nearftpor tionzn as WEILKHQWIL-r;

The casing 50 has sat: diametrally opposite pqsition ns longitudinal,,rearwardly extending slows-60 which; pre-fer=,-'10 ably align with,;the...-ribsn 27j inqthesinsulatingiicup 27,.

Atthe :center of the, iassem-hlyzrearwardlg of the t1amp, is placeda contact.button-fihwhicheng ges the 'ie nt fii contact Sionthelampand is idesirablyr oft rivet-dorm, U as shown, being riveted over at 630m the rearward-Sided! of an insulating ,disc \64.;and forminga .SPllDgH SQQKEt r65," on theside ofthencontaetlbutton remoteirom. theslanipi Theinsulatingtdisc .64 engages;the inside;ofzthecasing x' and is rsiidable. with respect, :thereto .to icompensate for s slighhdifierencessin the i position of. thelcentral- ,contaet;,,20 58 of. .the ,-la1np.,; and .the .disc has. ears 66; which extend out into and. are slidable in .the,.slots. 60;. of. thencasing...

Positioned rearwardly. of.,the...insulating .disc 64 is an insulatingsleeve 67- 1which seats in therearlof the, casing 50 and is heldiby spinning overnthe,rear.of.,casing..50 at 672T The. sleeve is heldagainsta shonldeik67 in-the... casing. Thesleeve .67jsupports. a movable contactex: tension. 68-whi'ch hasa spring. socket-:69, at its'jforward;v end and is flanged over beyond the sleeve 67 to engage, the sleeve at, 70. ,The. sleeve.:67i extends v.arcnindfllhe'. 30 outside'of. the spring socket-atfllffflTlie movablefswitchl contact extension.68TextendsIrearwardly."and in guiding. relation with the opening ,29' "at thece'nter of .diserlikef bottom 28 and at itsjrearward end is fsurroundedrby contact Washer 72' which is secured. and held' on the exten sion 68.by riveting at.73. Thus in one position of the. movable switch contact extension the washer 72' engages the contact.38.and inthe other position it engagesthe; riveti47.

Surrounding andinspaced relation tothelswitch con- 40 tact extension 68 is placed a contact spring 74of helical compression type which at one end engages contact 32'- and at the otherend engages the. rear. of casing 50.

Placed between spring sockets 65 and, 69 is a helicalcompression spring'75." In operation of the deviceofi Figures '1 to 5, the light;

will light normally by current flowing through jcontact- 38,"W3Sh'l'"72, movable Iswitch ;con tact; extension 68,- spring 75"and contact button 621.10 thereenter-contact of the lamp-andthen front-the outside of the lampthrough" barrel"51', casing 50, contact spring 74 and contact 62;; Light from the illuminating portion of; the bulb which-- passes out laterallyin part strikes the-refieetor 53 and,

is reflected forward.

When it is desiredto-tesL-the operator'pushejs inon-t-he 55 cover'g54, which moves the movable switch{contaet-ex-- tension to disconnect from contact 38' and connect "to rivet 47 which illuminates the 'bulb ona test circuit; which also'includes the contact 32.

On release of. the pressure on the cover 54, the as: sembly returns to the position for normallighting :as; shownin Figure 4.-

In'order'to replacera bulb it is merely necessary to tin-- screw. the cover and barrel assembly from; the casing, grasp the bulb onxthefiange- 57ftake out. the oldbulb' andput in a new bulb. When the coverrba'rrel assembly is screwed. back into the .casing iflthebulb is slightly longen. this is compensatedffor by compression of spring 75.,

Also when the:cov e1tispushedinwardly to'test, the testxontacts are. closed before: the. rearv of the 7 cover engages. the. :flahge on. the; ho'usingr andgovertravel,iis permitted by compressionof spring fthus assuring good contacts. in :the test positio'n...

The device can be used withindicator-lights which I lack. the-t st.-swit h-. ..Thus in .Ei ure -.6., the. srame... ,oversm barrel and lamp assembly is placed in a housing 78 which is externally supportednlike the housing 22, and is internally threaded at 78 to engage the outside of the barrel. In this form an insulating disc 64 is slidable inside the housing and supports the .contact button 62 as already described. The rearward portion of the housing has a shoulder 80 and-is .enlar'gedrtb n'eceive an insulating discr67' which engages a contact element 68' which in this-base is fixed ,a'ndriveted-to theldisjibut otherwise. resembles theflfixtension -68.: LThFclrean; of. the hoiising is spun over at 37 to hold disc 67'. The spring 75 allows for differencestkin length fofthe lamp. n

One of the requinernents,.is thatdtheeco ler 54 must stand an axial force of 200 pounds; and this is possible due to the advantageous dome-shaped form of the cover and the excellent support which it is given.

Havingrthusflescnibedaour invention what wesclaim asnewzandiidesire to securezbyrlsetters Patent is :1

1. In an indicator light, a d0II'lB'ShZ1pd' transparent:.=.= cover-.haYing a; hollow interion; av tubular barrel? joined to th -c ver tat-athemp nt endxandnhahing a reverse conical... t-zont-thesbanelr adjoining thenover, -an.1elec.tric, light-.;-:; bulb extending through the barrel into the hollowlof thew. cover. andzhavingqits lightrgiuingiprortionz located substan: tially;betweenntheureverse conical face pf :thebarrel and; 1 the opposite end oftthe ;,.cove1,-;;the zelectric lightbulbs: having'a;flange beyondthe'endof the barrel-remote from the:cover extending puts t0 ia diameter greaten than :the; barrehandgatubulancasingisurrounding the .fiange of the. eleetricjight bulbi and=Stlnrotntlding-'and.-inter.th1ieacled ;withtv the barrel.

2.11m ianziindicator light; la tubular honsing, ,a switch contact at oneyendof .the,.-housing, .a tubular casinginside 1 the housing and reciprocable withrespectthereto; a tu-": bular. ,barreL threaded .within; the; casing, a transparent covernqntthe endtof thebarielrremote from ithercasing any t electric lamp within the barrel and covenya fixed contact within 'the housing, interniediatenbetween .-.the ends-.ands ingda central opening, anelectrically COnClIlti11g:Spr i,ng-, between the fixed contact and the casing, and a switch ex tension, interconnected :wvith the ;.lamp at one end. and? extending thrnugh theppening andin one position of iheu casing engaging the, s t/itch.contact.v

3.1In ran indicator,.light,,a. tubular, h0using, a metallic: I casing in spaced relation to the housing insulated there:- from and ,mQYable, longitudinally, 7 thereof;;.. a barrel: threaded-into -the casing, a. transparent-,domc-sh ped hollow.cov. e 1: onihe'findof thebarrel remote fromth'e casing a lamp- I withinwthem barrel, and casing, an insulating mount-ing discsecuredto the casing rearwardlybf the: lamp andslidable longitudinally of thecasing, a contact button in the insulating dise'engaging the centralcontact, on the lamp and having a socket disposed oppositelyto the lamp, a fixed contact mounted inside the'housing be tween thc-rear of the housing and the casing, insulated from-the-housing-and having a-central*opening,"a contact spring extending from the fixed .contactto the end of the casing remotefroin the lamp; aninsulating element insidethe casing betweenithel-first v insulating disc and the fixed contact;v firstand second-:opposediswitchcontacts atthe rear of.rtheehousingmud-insulated:therefrom, a contact extension extending from-the insulating element throughthe openingat the center-bf theifixed-contactand in one; posigtiont Qf the easing'eng-aging the.first;switch :contact,; the contact.extensien hav-invasocket on the end disposedw toward the lamp and an :overtravel spring extending; between the contact button and the contact-:extensionand tittingjntothesockets, thecontact extension in another position engaging the second switchrcontaet...

4. In; an indicator l ight a tnbular,...housing,, a first; nsuletingse m idetherhcusin at one d h eon... a metallic'casing; in insulated spaced relation to thefjhous-- ing and movable longitudinally thereof, abarrel threaded. P into'thecasing; a. transparent dome-shaped hollow-cover on the end of the barrel remote from the casing, a lamp within the barrel and casing, an insulating mounting disc secured to the casing rearwardly of the lamp and slidable longitudinally of the casing, there being a longitudinal slot in the casing extending from the insulating disc to the end of the casing remote from the cover and there being ears on the insulating disc extending into the longitudinal slots, a contact button at the center of the insulating mounting disc engaging the central contact on the lamp and having a spring socket on the end remote from the lamp, a fixed contact inside and in spaced relation from the housing intermediate between the two ends and having a central longitudinal opening, a contact spring between the fixed contact and the end of the casing remote from the cover, a second insulating element secured to the rear of the casing, there being longitudinally slidable interlocks between the first insulating element and the casing in line with the slots on the casing, opposed switch fixed contacts in the rear of the housing insulated therefrom, a movable contact mounted at the center of the second insulating element and extending from the second insulating element toward the nearer switch contact and in the retracted position of the housing engaging the nearer switch contact, the movable contact having a spring socket disposed on the side toward the lamp, an

overtravel spring occupying the spring sockets between the contact button and the movable contact, and the movable contact in rearward position engaging the more remote switch contact.

5. In an indicator light, a dome-shaped transparent plastic cover having a hollow interior, a tubular barrel having an interior diameter generally in alignment with the hollow interior of the plastic cover, having an annular reverse conical surface on its end adjoining the cover, and joined to the cover over the reverse conical surface and over the outside of the barrel, and an electric light bulb inside the barrel and the hollow of the cover, engaging the interior of the barrel and having its lightgiving portion between the reverse conical surface of the barrel and the end of the cover remote from the barrel, the reverse conical surface acting as a reflector for the bulb.

References Cited in the file of this patent UNITED STATES PATENTS 2,424,574 Marco July 29, 1947 2,538,475 Skrastin Jan. 15, 1951 2,681,980 Herrington June 22, 1954 2,710,955 Halleberg et al June 14, 1955 

